The present invention relates to apparatuses and methods for universal joints, and more particularly, to booted universal-joints in which the joint members are coupled to one another by means of pins configured to be more securely connected.
A universal-joint (see FIG. 1) is a component that allows transmission of rotational motion and torque through angled axes. One common use for these universal-joints, particularly booted universal-joints, is the flap deploying system of commercial aircraft. As shown in FIG. 6, grease may be injected by means of an injection device 88 squeezed between the boot and a joint member of the universal joint, which results in stretching the boot.
As a result of the constant bending loads, which may even include alternating bending loads, and the need to endure long term stress, for example twenty years of such stress in the case of a commercial aircraft flap deploying system, the security of the booted universal joint is of paramount concern, both in terms of the security of the universal joint itself as well as in terms of the security of the connection between the boot and the universal-joint.
Retaining rings, typically made of rigid aluminum, are often used to seal the boot against grease leakage and to maintain the position of the boot ends in place. Accordingly, a further problem is that the retaining rings pressed around the ends of the boot lightly compress the soft rubber boot toward the joint members, but since the boot is made of soft silicon rubber, the ends of the boot tend to easily move between the retaining rings and the joint members and eventually pull out of the universal-joint. This is exacerbated by the typical 12.5 degree articulation angle in the boot that creates tension on the outer face of the boot, encouraging the boot to be pulled out of the retaining rings, as shown in FIG. 11.
There is a compelling need to have a booted universal joint which can successfully and securely endure twenty years of bending loads and stress. It would be particularly advantageous to have such a booted universal joint that is secure both in terms of the connection between the boot and the universal joint as well as in terms of the security of the connection between the internal parts of the universal-joint.